Edelbrock 1406

[Robert Collier]

Do I need the original spacer with the new Edelbrock 1406?

I did not plug up the intake holes in the "gutter" will that be an issue with the new carb?

Last question, is the vacuum advance for the distributor a full time vacuum or is it a part time vacuum?

Thank you everyone for your time

[Jason Edge]

The stock intake to carb insulator will work but has grooves cut out of the front for the exhaust gutter, and a rear channel on top rear.  You can use it if front PCV nipple is plugged but I believe the extra cutouts and groove compromises the insulation factor a bit. Also, for anyone running a 1411 with the larger front primaries, the stock spacer will not work as the front ports match the smaller front ports on the intake manifold.  For 1406 application, the stock spacer would be an OK spacer / insulator but if you have a nice stock one, I would remove and set aside incase you want to go back factory some time, and invest in a decent spacer designed for the 1406 such as the Trans-Dapt 2446 like I used.  If you have already spend $300 to upgrade to a new modern carb, I see the $40 to $50 in a decent spacer/insulator as a good investment.

[Jason Edge]

Yes, you have to remove the intake to block the bottom opening of the internal choke tube.

When I first did my intake and carb project (seen here: http://6364cadillac.ning.com/profiles/blogs/jason-s-carburetor-inta...) I only blocked the 2 internal choke tube end openings and the 2 top gutter openings.  I did not initially block the center cylinder head to intake exhaust channel.

I blocked the 4 openings to the center exhaust channel since:

1)  the Edelbrock 1406/1411 has the electric choke and did not need the choke tube to feed the hot air to a mechanical choke

2) the center choke tube often rots & cracks allowing fire hot gases out the choke tube ends which can be dangerous (so both ends of the choke tube were blocked)

3) The new Edelbrock Design did not need the blast of exhaust gas directly underneath the carb via the gutter (so those two gutter holes were blocked)

NOTE: When originally set up, I was also running dual exhaust and did not have the heat riser, which on cold start-up shuts off the exhaust flow out on the left driver side exhaust manifold forcing hot gases across the intake channel for faster engine fuel/air heat-up.  Even so, you still get unforced bypass exhaust gases flowing across that channel as I noticed my paint continuing to burn off in this area.  I measured the temps with a heat gun and was still getting a 300+ degree reading across the center port .  I have posted video showing the difference in temps on the intake with heat riser removed but with the center cylinder head to intake channel still open.  Just from the bypass gases the center is about 305 degrees vs the 195 degrees on the ends of the intake.  Here is a link to the video: http://6364cadillac.ning.com/video/1964-cadillac-intake-heat-temps

NOTE!: If you are running the stock set-up with the heat riser intact and functioning you cannot block the cylinder head to intake center exhaust port as seen above. If you do, your left exhaust will be blocked and engine will run like crap on startup until heat riser opens.   I blocked mine using heavy guage galvanized roofing steel because I wanted to further reduce the heat on the center exhaust channel across intake. To be able to do that and run stock exhaust I had the butterfly removed from my heat riser on the stock single pipe exhaust I am now running.

SUMMARY: If you are running a 1406 or 1411 you need to block the ends of the heat choke tube since you are not using it and leaving it open even if you have a solid internal tube, could eventually lead to problems if it ever cracks or corrodes open exposing the both ends to fire hot gases. You also want to close the top gutter holes to prevent those same hot gases from hitting the carb insulator.  IF, and a big IF, you do not plan to use the heat riser you can block the center cylinder head to intake channel further reducing the temps on center of intake beneath carb.

I will copy this to my carb/intake project thread for reference as this seems to come up often.

[Jason Edge]

I've never seen any but you can open up and port and polish the front primaries on the stock intake as I did. Of course that could be a later mod to tweak a bit more performance.

[Chris Codd]

Jason, I just purchased the 1406. Are there any aftermarket intake manifolds that bolt directly onto the 429? 

[Robert Collier]

Jason, I just want to clarify. Either way will I have to take of the intake to plug up the choke tube or to block of the intake exhaust channel?

What did you block of the intake exhaust channel with?

[Jason Edge]

The PCV inlet is built into the base of the 1406, so instead you need a standard Edelbrock spacer/insulator. I went with a 3/8" spacer/insulator that raised it about the right height.

If you blocked off the center intake exhaust channel between the cylinder heads and intake (as I did below in my engine rebuild last year, you will be fine. If not, you will want to plug both holes at the ends of the internal choke tube, and the top gutter holes.